Transcript: The history of life on Earth is not a simple linear progression from simple to more complex, from bacteria to us. There have been many twists and turns in this tale, many evolutionary dead ends. Chance effects are important on the history of life, for example, the role of giant...

Transcript: If planetary scientists are asked to speculate on the most possible sites for life within the solar system, they will generally give five places: Mars, Venus, Europa, Titan, and Io. These five places are significant. Mars is a traditional place where we might imagine life could have...

Transcript: It’s particularly important to consider the possibility of life on or in the gas giant planets of the solar system because these are the type of planets that have been found around nearby stars. Over a hundred extrasolar planets are now known, and most of them are Jupiter-like or...